Lowering peak energy demand with a bank of lead-acid batteries in the basement

Background: For stationary storage in a moderate climate, such as in a basement, lead-acid batteries still have a total cost of ownership comparable to lithium-ion batteries.

According to Samantha Page

In the basement garage of a high-end apartment building in the middle of New York City, a few electricians are quietly installing a century-old product that is now poised to revolutionize an industry — and maybe lead the United States into a carbon-neutral future.

Taking up about two parking spaces is a wall of boxes. They are simple lead-acid batteries, similar to what keeps the lights on in your car. But these batteries are linked together, connected to the building’s electricity system, and monitored in real time by a Washington-state based company, Demand Energy. Demand’s installation at the Paramount Building in midtown Manhattan is going to lower the building electricity bills and reduce its carbon footprint, even while it doesn’t reduce a single watt of use.

Every night, the batteries charge up. Every day, they run down, providing a small portion of the building’s energy and reducing the amount of power it takes off the grid. This cycle of charging during low-use times and discharging during high use times helps level out the Paramount’s electricity use.

and

American home bills usually have a flat rate for the amount of electricity the resident uses. No matter when it’s used, or how quickly power is drawn, the rate is the same amount per kilowatt hour. Flat rates are like an odometer saying how many miles were drive — or, in this case, how many kilowatt hours (kWh) have been used. But for commercial and industrial properties, including residential apartment buildings, the electricity bill also has a demand charge. The demand charge acts like a speedometer: Not only is a business charged for the total amount of electricity it uses, it is also charged for how quickly power is taken. A business will receive a higher bill for using 10 kWh in an hour than for using the same 10 kWh over, say 10 hours. In New York, demand charges make up, on average, half of commercial and industrial customers’ bills.

Electricity rates are designed like this because utilities don’t like peaks in demand. Peaking plants are expensive, wasteful, and dirty. But from the utility’s perspective, putting a lot of electricity on the grid is also bad news. The higher the peak demand, the more infrastructure — wires, generators — has to be built. And transmission congestion means a less efficient system. (Line loss, a phenomenon in which not all the electricity gets from point A to point B, is greater when the transmission system is overloaded). Not to mention the risks of brownouts and blackouts that increase with too much strain on the grid.

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